Method and apparatus for determining if an optical disk originated from a valid source

ABSTRACT

A method and apparatus for determining if an optical disk originated from a valid source, the method and apparatus scanning one major surface of the optical disk for imperfections, storing the locations of the imperfections relative to a datum, comparing a parameter of each of the locations of the imperfections with corresponding parameters of a master disk of known source for determining if the disk originated from the source from which the master disk originated.

CROSS REFERENCES TO RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.10/868,317, filed on Jun. 15, 2004, which claims priority from IrishPatent Application No. S2003/0443, filed Jun. 16, 2003, which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for determiningif an optical disk originated from a valid source.

BACKGROUND OF THE INVENTION

Due to the ready availability of duplicating equipment, counterfeitingof optical disks, in particular, counterfeiting of CD-ROMs and music CDsis becoming a major problem on a global scale. With the ever increasingsophistication of duplicating equipment, in general, it is virtuallyimpossible to identify counterfeit software on CD-ROMs. Similar problemsarise in connection with counterfeit music CDs.

SUMMARY OF THE INVENTION

The present invention is directed towards providing a method andapparatus for determining if an optical disk originated from a validsource.

According to the invention there is provided a method and apparatus fordetermining if an optical disk originated from a valid source, themethod and apparatus scanning one major surface of the optical disk formechanical surface imperfections, storing the locations of the surfaceimperfections relative to a datum, comparing a parameter of each of thelocations of the surface imperfections with corresponding parameters ofa master disk of known source for determining if the disk originatedfrom the source from which the master disk originated.

In one embodiment of the invention the major surface of the disk whichis scanned is the surface through which laser light is passed to thereflective surface for reading recorded data on the optical disk.

In another embodiment of the invention the major surface of the disk isscanned using dark field scanning. Preferably, scanning of the majorsurface is carried out by directing light towards the major surface at arelatively small angle to the major surface, so that only light incidenton a surface imperfection is reflected at an angle substantiallyperpendicular to the major surface. Preferably, the light directedtowards the surface is directed at an angle in the range of 0° to 30° tothe major surface.

In one embodiment of the invention light reflected from surfaceimperfections on the major surface is reflected to a camera, andpreferably, to a digital camera. Ideally, the disk is mounted relativeto the digital camera so that one of the disk and the digital camera ismoveable relative to the other in X-Y directions perpendicular to eachother for facilitating scanning of the entire surface of the disk.

In one embodiment of the invention the locations of the surfaceimperfections are stored by their respective X-Y co-ordinates relativeto the datum, and the X-Y co-ordinates are subsequently converted intoangular co-ordinates of the disk. In another embodiment of the inventionthe parameters of the locations are sequentially compared withcorresponding stored parameters of master disks until a match has beenmade.

In one embodiment of the invention the datum for the disk being scannedis established relative to one of the surface imperfections, and thecomparison with each master disk is made, commencing with theestablished datum position, and in the absence of a match, a new datumbased on another surface imperfection of the disk being scanned isestablished and the parameters of the disk are compared with thecorresponding parameters of the master disks, and preferably eachsurface imperfection is used as a datum.

Alternatively, the surface imperfections at each of a plurality of radiiare integrated over 360° of the disk of each radius.

Additionally the invention provides apparatus for determining if anoptical disk originated from a valid source, the apparatus comprising ascanning means for scanning a major surface of the disk for detectingmechanical surface imperfections, a computing means for computing thelocation of each surface imperfection, a secondary storing means forstoring the locations of the surface imperfections, and a means forproviding access to a primary storing means which stores parameters oflocations of surface imperfections of master disks from known sources,and a comparing means for comparing parameters of the stored locationsof the disk being scanned with corresponding parameters of the masterdisks for determining if the disk originated from a valid source.

In one embodiment of the invention the computing means comprises acomputer.

In another embodiment of the invention the scanning means comprises aplatform capable of planar movement in X-Y directions, and a camera forcapturing images of surface imperfections.

In one embodiment of the invention the scanning means comprises a darkfield scanner, and the dark field scanner comprises a means fordirecting light at the major surface of the disk at a relatively smallangle to the major surface, and preferably, at an angle in the range of0° to 30°, so that only light incident on a surface imperfection isreflected to the camera, and preferably, is reflected substantiallyperpendicularly from the major surface.

In one embodiment of the invention the camera is a digital cameracomprising a 1,000 by 1,000 matrix of pixels, and ideally, the pixelsare of 10 microns in size.

In a further embodiment of the invention the camera is capable of 2× to10× magnification of the image, and preferably 2× to 5× magnification.

In a still further embodiment of the invention the computer carries outthe comparison between the parameters of the disk and the correspondingparameters of the master disk.

Advantages of the method and apparatus according to the inventioninclude provision of optical medium inspection for accuratedetermination of the source of the optical medium. A high speedinspection and magnification method and apparatus is provided forreducing substantially the incidence of optical media and softwarepiracy.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will bemore clearly understood from the following description of an embodimentthereof, which is given by way of example only, with reference to theaccompanying drawings, in which:

FIG. 1 is a diagrammatic representation of apparatus according to theinvention for determining if an optical disk originated from a validsource,

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1,

FIG. 3 is a top plan view of an optical disk, and

FIG. 4 is a transverse cross-sectional side elevational view of theoptical disk of FIG. 3.

Referring to the drawings and initially to FIGS. 1 and 2, there isillustrated apparatus according to the invention, indicated generally bythe reference numeral 1, for determining if an optical disk, in thisembodiment of the invention a CD-ROM disk 2, originated from a validsource. The apparatus 1 comprises a dark field microscopy scanner 4 forscanning the disk 2, the validity of the origin of which is to bedetermined. The scanner 4, as will be described below, scans a majorsurface 5 of the disk 2 for identifying mechanical surface imperfectionson the major surface 5, such as the imperfection 8 of the disk 2illustrated in FIG. 4. In this embodiment of the invention the majorsurface 5 being scanned is the surface through which laser light ispassed to the reflective surface 9 of the disk 2. A computing means, inthis embodiment of the invention a PC 10 computes and stores the angularlocations of the surface imperfections 8. On completion of a scan of thedisk 2 the PC 10 then compares a parameter of the location of eachsurface imperfection with a corresponding parameter of surfaceimperfections of master disks stored in a primary store, namely, aread-only memory (ROM) 12 for determining if the disk 2 has originatedfrom a valid source. The apparatus 1 and its operation will be describedin more detail below, however, before proceeding to describe theapparatus 1 further, the compact disk 2 will first be described in moredetail with reference to FIGS. 3 and 4.

The CD-ROM disk 2 comprises a transparent layer 15 of polycarbonatematerial through which laser light in use is passed to a reflectivelayer 16 which contains the data to be read from the CD-ROM disk 2. Alabel side layer 17 also of polycarbonate material is laminated to thereflective layer 16. Thus, the CD-ROM disk 2 comprises the major surface5 on the transparent polycarbonate layer 15, and a major surface 18 onthe label side 17. However, for the purpose of the invention only themajor surface 5 on the transparent polycarbonate layer 15 is relevant.The CD-ROM disk 2 has an outer border area 20 and an inner border area21 on which no data is recorded. A data recorded area 24 located betweenthe inner and outer border areas 20 and 21 contains the recorded data.In this embodiment of the invention only the data recorded area 24 isscanned for mechanical surface imperfections. It has been found thatmechanical presses, in which CD-ROM disks 2 are pressed, impress surfaceimperfections on the transparent major surface of the CD-ROM disks.These surface imperfections result from corresponding imperfections inpressing plates of the presses, and effectively form a fingerprint fromwhich all disks pressed on a particular press can be identified. Thepresent invention is based on this fact that each press impresses acorresponding identical pattern of surface imperfections on all diskspressed on that press.

Returning now to the apparatus 1, and referring in particular to FIGS. 1and 2, the scanner 4 comprises a platform 30 on which the disk 2 to bescanned is secured. The platform 30 is incrementally moveable in X and Ydirections for facilitating a complete scan in incremental steps of themajor surface 5 of the disk 2. A camera 32, in this embodiment of theinvention a digital camera, is fixedly mounted above the platform 30,and a lens 33 which provides a magnification of between 2× and 10×magnifies the image of a scanned area to the camera 32. A dark fieldlight source provided by an annular light source 35 is located beneaththe camera 32, and is co-axially aligned with the lens 33, so that lightreflected perpendicularly from the major surface 5 of the disk 2 passesthrough a central opening 36 of the annular light source 35 to the lens33. The annular light source 35 in this embodiment of the inventioncomprises a plurality of light emitting diodes which are arranged toemit light radially towards a central axis defined by the annular lightsource 35 at a relatively small angle to the major surface 5, which inthis embodiment of the invention is approximately 30° to the majorsurface 5.

Light indicated by light rays 38 in FIG. 4 incident on the major surface5 is refracted into the transparent layer 15 to the reflective layer 16of the disk 2 and is reflected from the reflective surface 9 formed bythe reflective layer 16 through the major surface 5 at an angle to themajor surface 5 substantially similar to the angle of incidence of therays 38 to the major surface 5. The reflected light is illustrated bythe light rays 39. However, light from the annular light source 35incident on a surface imperfection 8 is reflected substantiallyperpendicularly to the major surface 5 by the imperfection through thecentral opening 36 of the annular light source 35 to the lens 33, and inturn to the camera 32, see the reflected rays 39 b in FIG. 4.

The camera 32 is a high resolution CCD camera having a matrix of pixelsof the order of 1,0002 of approximately 10 microns size, and when themagnification of the lens 33 is set between 2× and 5× an image 40 ofapproximately 2 mm to 5 mm square of the disk 2 is captured, see FIG. 3.As each image 40 is captured, the platform 30 is incremented in theappropriate X or Y direction to capture the next adjacent image 40 untilthe entire data recorded area 24 has been scanned. On completion of thescanning the individual image frames 40 are then pieced together by thePC to form a full map of the major surface 5 of the disk 2 whichincludes all the detected surface imperfections 8 and their locations onthe major surface 5. The map of the major surface 5 is stored in the PC.

At this stage, any one of a number of suitable algorithms may be usedfor comparing the map of the major surface 5 with corresponding maps ofmaster disks of known sources which are stored in the ROM 12 fordetermining if the disk 2 originated from one of the valid sources. Oneparticularly suitable algorithm requires integrating the surfaceimperfections over 360° of the disk 2 at each of a number of radii fromthe centre of the disk 2 and comparing the integrated values at each ofthe radii with corresponding integrated values of the master disks toestablish if a match exists. Typically, the surface imperfections areintegrated over the 360° of the disk at each radius in incremental stepsof 2 μm to 5 μm (object pixel size) from the inner radius of the datarecorded area 24 to the outer radius of the data recorded area 24. If amatch is found, then the disk 2 is deemed to have originated from avalid source. In the absence of a match being found, then the disk isdeemed to be of unknown origin, and possibly counterfeit.

The PC 10 is programmable to facilitate entry and storage of additionalmaps of master disks, as new CD-ROM disk presses come on stream.Typically, a plurality of master disks from the same press, for example,10 to 100 disks are scanned by the apparatus 1, and the map of the majorsurface of each disk is stored. Depending on the algorithm used forcomparing a disk with the master disk, appropriate parameters of thelocations of the imperfections are averaged over the scanned disks, andthe average is then stored in an additional ROM. If, for example, thealgorithm for determining if a disk originated from a valid source orotherwise is that which has already been described, the integratedvalues of the imperfections over the 360° of the disks at the respectiveradii are averaged for each radius, and the respective averages for eachradius is stored.

In general, it is envisaged that it may not be possible to identify aspecific datum for each disk to be tested with a datum for a masterdisk, and in which case, the algorithm for comparing a disk with themaster disks just described is a particularly suitable algorithm.However, if it were possible to identify a specific datum for eachmaster disk and a corresponding datum on the disk of the disk beingtested, then the angular and radial locations of the respectiveimperfections 8 of the disk being tested can be determined from theangular datum and compared with corresponding imperfections from acorresponding angular datum on the master disk.

In use, where it is desired to determine if a disk originated from avalid source, the apparatus 1 is operated in a test mode, and the disk 2is placed on the platform 30. The disk 2 is then scanned by the camera32 as the platform 30 is incremented in the X and Y directions until acomplete map of the data recorded area 24 of the major surface 5 of thedisk 2 has been made and recorded in the PC 10. Depending on thecomparison algorithm being used, the PC 10 then compares the appropriateparameters of the stored map of the disk 2 with corresponding parametersof master disks stored in the ROM 12. If a match is found, then the disk2 is determined as having originated from a valid source. In the absenceof a match, the disk is determined as being of unknown origin, andpossibly counterfeit.

Where it is desired to store further master maps or master parameters ofmaster CD-ROMs of known sources, the apparatus 1 is operated in newentry mode, and a plurality of disks, typically, 10 to 100 disks from aknown source are scanned as already described and a map of the datarecorded area 24 of the major surface 5 of each disk 2 is prepared andstored in the PC 10. Appropriate parameters of the surface imperfectionsof the scanned disks are averaged and stored in a new ROM 12.

While the apparatus has been described as comprising a ROM which storesmaps of the relevant major surface of master disks of known source, itis envisaged that in certain cases the apparatus may not include thestore of data of master disks, but rather, the master disk data would bestored centrally, and the apparatus according to the invention would beable to access such a central store over a suitable communication link,for example, through a telecommunication network, the internet, orotherwise.

It is also envisaged that as disks of unknown origin are confirmed asbeing counterfeit, a master map or master parameters of the counterfeitdisk may also be stored in the apparatus or centrally. Thus, theapparatus could also compare disks, the source of which is beingdetermined with the master map or master parameters of the counterfeitdisk in order to confirm if a disk of unknown source can be confirmed asbeing counterfeit.

While particular algorithms for comparing the parameters of surfaceimperfections of a disk with those of master disks have been described,any of various other suitable algorithms may be used.

Although the invention is described herein for determining if a CD-ROMoriginated from a valid source it should be appreciated that theinvention could be applied to other media and packaging, such as tapeand video packaging or other packaging for content that originates froma source with distinctly identifiable physical characteristics.

While the method and apparatus described herein involves use ofimperfections on a major surface of an optical disk, it should beappreciated that sub-surface imperfections or other mechanicalcharacteristics of other surfaces may be considered.

The invention is not limited to the embodiments hereinbefore described,which may be varied in construction and details and the foregoing andvarious other changes, additions or deletions in the form and functionof the apparatus and method described herein and recited in the claimsmay be made without departing from the spirit and scope of theinvention.

1. A method for determining if media originated from a valid source, themethod comprising the steps of: scanning a surface of the media forimperfections; storing the locations of the imperfections relative to adatum, wherein locations of the imperfections are coordinates relativeto the media; comparing a parameter of each of the locations of theimperfections with corresponding parameters of a master media of knownsource for determining if the media originated from the source fromwhich the master media originated.
 2. The method according to claim 1,wherein the media is an optical disk and the surface of the disk whichis scanned is a surface through which laser light is passed to thereflective surface for reading recorded data on the optical disk.
 3. Themethod according to claim 1, wherein light reflected from imperfectionson the surface is reflected to a camera.
 4. The method according toclaim 1, wherein locations of the imperfections are stored by respectiveX-Y coordinates relative to the datum, and the X-Y coordinates aresubsequently converted into angular co-ordinates of the disk.
 5. Anapparatus for determining if media originated from a valid source, theapparatus comprising: a scanning means for scanning a surface of themedia for detecting imperfections; a computing means for computing thelocation of each surface imperfection; a secondary storing means forstoring the locations of the surface imperfections; and a means forproviding access to a primary storing means which stores parameters oflocations of surface imperfections of master media from known sources;and a comparing means for comparing parameters of the media beingscanned with corresponding parameters of the master media fordetermining if the media originated from a valid source.
 6. Theapparatus according to claim 5, wherein the scanning means comprises aplatform capable of planar movement in X-Y directions, and a camera forcapturing images of surface imperfections.